This invention relates to a drive authorization system for an electric drive.
With conventional drive authorization systems, it is possible to circumvent an electronic immobilization function by exchanging components, e.g. control units, which are involved in the drive authorization system. For this reason, in order to increase security, an electronic immobilization function can be coupled mechatronically to a sensor system or actuator system which is difficult to access on the internal combustion engine.
German Patent specification DE 43 36 212 C2 describes a sensor arrangement for detecting cylinders in an internal combustion engine. The sensor arrangement described comprises an encoder disc for detecting a defined position of a crankshaft of an internal combustion engine, a reference mark arranged on the encoder disc, a detector associated with the encoder disc, and a control means which evaluates the signal of the detector. The reference mark marks a predefined position of the crankshaft which is assigned to the reference mark. In order to code the internal combustion engine, the reference mark is assigned to a position of the crankshaft which is specific to the internal combustion engine.
German Publication DE 10 2005 039 585 A1 describes a drive authorization system with an electronic immobilization function. The electronic immobilization function described is coupled to a crankshaft sensor. Via an encoder wheel arranged on the crankshaft, the crankshaft sensor detects the position and/or the rotational speed of the crankshaft and transmits it to an engine control unit which enables the electronic immobilization function. The encoder wheel comprises a predefined number of teeth which are distributed along the circumference of the encoder wheel by means of a code. The teeth generate an encoded rotational speed signal which is detected by the crankshaft sensor and can be decoded by the engine control unit. The engine control unit enables the immobilization function only after successful decoding of the encoded rotational speed signal.
The object of the invention is to devise a drive authorization system for an electric drive which permits mechatronic linking of an electronic immobilization function to an electric drive and hence increased protection against theft.
The invention solves this problem by providing a particular drive authorization system for an electric drive.
Advantageous embodiments and developments of the invention are also set forth in the claims.
According to the invention, to implement an electronic immobilization function, the positions and/or the number of active rotation angle sensors are/is made encodable. An evaluation and control unit is used for determining a current position of a movable element of an electric drive, with a predefined number of field coils decoding the encoded positional information of the active angle of rotation sensors. In such a case, operation of the electric drive is possible only after successful decoding of the positional information. Furthermore, the evaluation and control unit for operation of the electric drive determines a current position of the movable element from several items of positional information which are made available by a predefined number of rotation angle sensors.
The linking of the function of immobilization to a vehicle part which is difficult to exchange, such as the electric drive, advantageously makes it considerably more difficult to exchange components in order to circumvent the immobilization function. The linking takes place according to the invention via the embodiment, individual to the drive, of the rotation angle sensor system for determining the mechanical position of the angle of rotation of the movable element of the electric drive, which is necessary in order to operate a contact-free electric drive. The embodiment, individual to the drive, of the rotation angle sensor system is decoded in the evaluation and control unit of the vehicle in order to be able to control the electric drive correctly. Thus the invention makes it possible to realize an effective immobilization function, so that simply exchanging the control unit is not sufficient to circumvent the electronic immobilization function. A further advantage is that the rotation angle sensors, in the technical embodiment in the electric drive of the vehicle, are accessible from the outside only with difficulty, and thus make rapid manipulation difficult.
In an embodiment of the drive authorization system according to the invention, the number of positions present for the active rotation angle sensors is greater than the number of active rotation angle sensors. To unambiguously determine the position of the movable element, at least three angle of rotation sensors are necessary, which are arranged at three different positions. If more positions for the possible arrangement of angle of rotation sensors are now made available, the angle of rotation sensors for each electric drive can be arranged individually. The evaluation and control unit can, for example, be adapted to the changed positional information of the angle of rotation sensors by a decoding algorithm, in order to set the movable element of the electric drive in motion. An incorrect evaluation of the positional information owing to a wrongly assumed position of the angle of rotation sensors here does not result in a movement of the movable element of the electric drive. Apart from the positions of the individual angle of rotation sensors, the number of active angle of rotation sensors, the positional information of which is evaluated for determining the position of the movable element, can also be encoded or varied. In addition, it is possible to arrange a rotation angle sensor at each of the possible positions and to couple it with the evaluation and control unit, so that the positional encoding is not immediately obvious.
In a preferred embodiment of the drive authorization system according to the invention, the evaluation and control unit decodes the encoded positional information of the active angle of rotation sensors with a decoding algorithm which can be enabled and activated by an authorized authentication element. An enabling signal for the decoding algorithm in the evaluation and control unit may be generated by an electronic ignition lock after successful authentication, the electronic ignition lock communicating with the portable authentication element via a communications link for authentication.
In a preferred embodiment of the drive authorization system according to the invention, the angle of rotation sensors are embodied as Hall effect sensors. In addition, the rotor has a rotor shaft which is connected to a permanent magnet. The rotation angle sensors embodied as Hall effect sensors then detect the positional information from which the position of the permanent magnet can be determined.